简体中文(ZH-CN) English(EN) 繁体中文(ZH-TW) 日本語(JA) 한국어(KO) Melayu(MS) Français(FR) Deutsch(DE)
Home > php教程 > php手册 > body text

C#DataTable detailed explanation

WBOY
Release： 2016-07-06 13:30:27
Original
1257 people have browsed it

Add reference using System.Data; Create table // Create an empty table DataTable dt = new DataTable(); // Create an empty table named "Table_New" DataTable dt = new DataTable( " Table_New " ); Create Column // 1. Create an empty column DataColumn dc = new DataColumn();dt.Columns.Add(dc); //

Add quote

<span style="color: #0000ff;">using</span> System.Data;
Copy after login

Create table

<span style="color: #008000;">//</span><span style="color: #008000;">创建一个空表</span>
DataTable dt = <span style="color: #0000ff;">new</span><span style="color: #000000;"> DataTable();
</span><span style="color: #008000;">//</span><span style="color: #008000;">创建一个名为"Table_New"的空表</span>
DataTable dt = <span style="color: #0000ff;">new</span> DataTable(<span style="color: #800000;">"</span><span style="color: #800000;">Table_New</span><span style="color: #800000;">"</span>);
Copy after login

Create Column

<span style="color: #008000;">//</span><span style="color: #008000;">1.创建空列</span>
DataColumn dc = <span style="color: #0000ff;">new</span><span style="color: #000000;"> DataColumn();
dt.Columns.Add(dc);
</span><span style="color: #008000;">//</span><span style="color: #008000;">2.创建带列名和类型名的列(两种方式任选其一)</span>
dt.Columns.Add(<span style="color: #800000;">"</span><span style="color: #800000;">column0</span><span style="color: #800000;">"</span>, System.Type.GetType(<span style="color: #800000;">"</span><span style="color: #800000;">System.String</span><span style="color: #800000;">"</span><span style="color: #000000;">));
dt.Columns.Add(</span><span style="color: #800000;">"</span><span style="color: #800000;">column0</span><span style="color: #800000;">"</span>, <span style="color: #0000ff;">typeof</span><span style="color: #000000;">(String));
</span><span style="color: #008000;">//</span><span style="color: #008000;">3.通过列架构添加列</span>
DataColumn dc = <span style="color: #0000ff;">new</span> DataColumn(<span style="color: #800000;">"</span><span style="color: #800000;">column1</span><span style="color: #800000;">"</span>,System.Type.GetType(<span style="color: #800000;">"</span><span style="color: #800000;">System.DateTime</span><span style="color: #800000;">"</span><span style="color: #000000;">));
DataColumn dc </span>= <span style="color: #0000ff;">new</span> DataColumn(<span style="color: #800000;">"</span><span style="color: #800000;">column1</span><span style="color: #800000;">"</span>, <span style="color: #0000ff;">typeof</span><span style="color: #000000;">(DateTime));
dt.Columns.Add(dc);</span>
Copy after login

Create row

<span style="color: #008000;">//</span><span style="color: #008000;">1.创建空行</span>
DataRow dr =<span style="color: #000000;"> dt.NewRow();
dt.Rows.Add(dr);
</span><span style="color: #008000;">//</span><span style="color: #008000;">2.创建空行</span>
<span style="color: #000000;">dt.Rows.Add();
</span><span style="color: #008000;">//</span><span style="color: #008000;">3.通过行框架创建并赋值</span>
dt.Rows.Add(<span style="color: #800000;">"</span><span style="color: #800000;">张三</span><span style="color: #800000;">"</span>,DateTime.Now);<span style="color: #008000;">//</span><span style="color: #008000;">Add里面参数的数据顺序要和dt中的列的顺序对应 <br>//4.通过复制dt2表的某一行来创建<br></span>dt.Rows.Add(dt2.Rows[i].ItemArray);
Copy after login

Assignment and value

<span style="color: #008000;">//</span><span style="color: #008000;">新建行的赋值</span>
DataRow dr =<span style="color: #000000;"> dt.NewRow();
dr[</span><span style="color: #800080;">0</span>] = <span style="color: #800000;">"</span><span style="color: #800000;">张三</span><span style="color: #800000;">"</span>;<span style="color: #008000;">//</span><span style="color: #008000;">通过索引赋值</span>
dr[<span style="color: #800000;">"</span><span style="color: #800000;">column1</span><span style="color: #800000;">"</span>] = DateTime.Now; <span style="color: #008000;">//</span><span style="color: #008000;">通过名称赋值
</span><span style="color: #008000;">//</span><span style="color: #008000;">对表已有行进行赋值</span>
dt.Rows[<span style="color: #800080;">0</span>][<span style="color: #800080;">0</span>] = <span style="color: #800000;">"</span><span style="color: #800000;">张三</span><span style="color: #800000;">"</span>; <span style="color: #008000;">//</span><span style="color: #008000;">通过索引赋值</span>
dt.Rows[<span style="color: #800080;">0</span>][<span style="color: #800000;">"</span><span style="color: #800000;">column1</span><span style="color: #800000;">"</span>] = DateTime.Now;<span style="color: #008000;">//</span><span style="color: #008000;">通过名称赋值
</span><span style="color: #008000;">//</span><span style="color: #008000;">取值</span>
<span style="color: #0000ff;">string</span> name=dt.Rows[<span style="color: #800080;">0</span>][<span style="color: #800080;">0</span><span style="color: #000000;">].ToString();
</span><span style="color: #0000ff;">string</span> time=dt.Rows[<span style="color: #800080;">0</span>][<span style="color: #800000;">"</span><span style="color: #800000;">column1</span><span style="color: #800000;">"</span>].ToString();
Copy after login

Filter rows

<span style="color: #008000;">//</span><span style="color: #008000;">选择column1列值为空的行的集合</span>
DataRow[] drs = dt.Select(<span style="color: #800000;">"</span><span style="color: #800000;">column1 is null</span><span style="color: #800000;">"</span><span style="color: #000000;">);
</span><span style="color: #008000;">//</span><span style="color: #008000;">选择column0列值为"李四"的行的集合</span>
DataRow[] drs = dt.Select(<span style="color: #800000;">"</span><span style="color: #800000;">column0 = '李四'</span><span style="color: #800000;">"</span><span style="color: #000000;">);
</span><span style="color: #008000;">//</span><span style="color: #008000;">筛选column0列值中有"张"的行的集合(模糊查询)</span>
DataRow[] drs = dt.Select(<span style="color: #800000;">"</span><span style="color: #800000;">column0 like '张%'</span><span style="color: #800000;">"</span>);<span style="color: #008000;">//</span><span style="color: #008000;">如果的多条件筛选，可以加 and 或 or
</span><span style="color: #008000;">//</span><span style="color: #008000;">筛选column0列值中有"张"的行的集合并按column1降序排序</span>
DataRow[] drs = dt.Select(<span style="color: #800000;">"</span><span style="color: #800000;">column0 like '张%'</span><span style="color: #800000;">"</span>, <span style="color: #800000;">"</span><span style="color: #800000;">column1 DESC</span><span style="color: #800000;">"</span>);
Copy after login

Delete row

<span style="color: #008000;">//</span><span style="color: #008000;">使用DataTable.Rows.Remove(DataRow)方法</span>
dt.Rows.Remove(dt.Rows[<span style="color: #800080;">0</span><span style="color: #000000;">]);
</span><span style="color: #008000;">//</span><span style="color: #008000;">使用DataTable.Rows.RemoveAt(index)方法</span>
dt.Rows.RemoveAt(<span style="color: #800080;">0</span><span style="color: #000000;">);
</span><span style="color: #008000;">//</span><span style="color: #008000;">使用DataRow.Delete()方法</span>
dt.Row[<span style="color: #800080;">0</span><span style="color: #000000;">].Delete();
dt.AcceptChanges();

</span><span style="color: #008000;">//-----</span><span style="color: #008000;">区别和注意点-----
</span><span style="color: #008000;">//</span><span style="color: #008000;">Remove()和RemoveAt()方法是直接删除
</span><span style="color: #008000;">//</span><span style="color: #008000;">Delete()方法只是将该行标记为deleted，但是还存在，还可DataTable.RejectChanges()回滚，使该行取消删除。
</span><span style="color: #008000;">//</span><span style="color: #008000;">用Rows.Count来获取行数时，还是删除之前的行数，需要使用DataTable.AcceptChanges()方法来提交修改。
</span><span style="color: #008000;">//</span><span style="color: #008000;">如果要删除DataTable中的多行，应该采用倒序循环DataTable.Rows，而且不能用foreach进行循环删除，因为正序删除时索引会发生变化，程式发生异常，很难预料后果。</span>
<span style="color: #0000ff;">for</span> (<span style="color: #0000ff;">int</span> i = dt.Rows.Count - <span style="color: #800080;">1</span>; i >= <span style="color: #800080;">0</span>; i--<span style="color: #000000;">)
{
　　dt.Rows.RemoveAt(i);
}</span>
Copy after login

Copy table

<span style="color: #008000;">//</span><span style="color: #008000;">复制表，同时复制了表结构和表中的数据</span>
DataTable dtNew = <span style="color: #0000ff;">new</span><span style="color: #000000;"> DataTable();
dtNew </span>=<span style="color: #000000;"> dt.Copy();
</span><span style="color: #008000;">//</span><span style="color: #008000;">复制表</span>
DataTable dtNew = dt.Copy();  <span style="color: #008000;">//</span><span style="color: #008000;">复制dt表数据结构</span>
dtNew.Clear()  <span style="color: #008000;">//</span><span style="color: #008000;">清空数据</span>
<span style="color: #0000ff;">for</span> (<span style="color: #0000ff;">int</span> i = <span style="color: #800080;">0</span>; i < dt.Rows.Count; i++<span style="color: #000000;">)
{
    </span><span style="color: #0000ff;">if</span><span style="color: #000000;"> (条件语句)
    {
         dtNew.Rows.Add(dt.Rows[i].ItemArray);  </span><span style="color: #008000;">//</span><span style="color: #008000;">添加数据行</span>
<span style="color: #000000;">    }
}
</span><span style="color: #008000;">//</span><span style="color: #008000;">克隆表，只是复制了表结构，不包括数据</span>
DataTable dtNew = <span style="color: #0000ff;">new</span><span style="color: #000000;"> DataTable();
dtNew </span>=<span style="color: #000000;"> dt.Clone();
</span><span style="color: #008000;">//</span><span style="color: #008000;">如果只需要某个表中的某一行</span>
DataTable dtNew = <span style="color: #0000ff;">new</span><span style="color: #000000;"> DataTable();
dtNew </span>=<span style="color: #000000;"> dt.Copy();
dtNew.Rows.Clear();</span><span style="color: #008000;">//</span><span style="color: #008000;">清空表数据</span>
dtNew.ImportRow(dt.Rows[<span style="color: #800080;">0</span>]);<span style="color: #008000;">//</span><span style="color: #008000;">这是加入的是第一行</span>
Copy after login

Table sort

DataTable dt = <span style="color: #0000ff;">new</span> DataTable();<span style="color: #008000;">//</span><span style="color: #008000;">创建表</span>
dt.Columns.Add(<span style="color: #800000;">"</span><span style="color: #800000;">ID</span><span style="color: #800000;">"</span>, <span style="color: #0000ff;">typeof</span>(Int32));<span style="color: #008000;">//</span><span style="color: #008000;">添加列</span>
dt.Columns.Add(<span style="color: #800000;">"</span><span style="color: #800000;">Name</span><span style="color: #800000;">"</span>, <span style="color: #0000ff;">typeof</span><span style="color: #000000;">(String));
dt.Columns.Add(</span><span style="color: #800000;">"</span><span style="color: #800000;">Age</span><span style="color: #800000;">"</span>, <span style="color: #0000ff;">typeof</span><span style="color: #000000;">(Int32));
dt.Rows.Add(</span><span style="color: #0000ff;">new</span> <span style="color: #0000ff;">object</span>[] { <span style="color: #800080;">1</span>, <span style="color: #800000;">"</span><span style="color: #800000;">张三</span><span style="color: #800000;">"</span> ,<span style="color: #800080;">20</span>});<span style="color: #008000;">//</span><span style="color: #008000;">添加行</span>
dt.Rows.Add(<span style="color: #0000ff;">new</span> <span style="color: #0000ff;">object</span>[] { <span style="color: #800080;">2</span>, <span style="color: #800000;">"</span><span style="color: #800000;">李四</span><span style="color: #800000;">"</span> ,<span style="color: #800080;">25</span><span style="color: #000000;">});
dt.Rows.Add(</span><span style="color: #0000ff;">new</span> <span style="color: #0000ff;">object</span>[] { <span style="color: #800080;">3</span>, <span style="color: #800000;">"</span><span style="color: #800000;">王五</span><span style="color: #800000;">"</span> ,<span style="color: #800080;">30</span><span style="color: #000000;">});
DataView dv </span>= dt.DefaultView;<span style="color: #008000;">//</span><span style="color: #008000;">获取表视图</span>
dv.Sort = <span style="color: #800000;">"</span><span style="color: #800000;">ID DESC</span><span style="color: #800000;">"</span>;<span style="color: #008000;">//</span><span style="color: #008000;">按照ID倒序排序</span>
dv.ToTable();<span style="color: #008000;">//</span><span style="color: #008000;">转为表</span>
Copy after login


Related labels：
sys using Quote Add to Detailed explanation
source：php.cn
Previous article：[Android] Chapter 3 (5) Layer display Next article：Dive deep into C# class methods
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Latest Articles by Author
Latest Issues
Nuxt 3 won't render in SSR So I've run into a problem where I'm trying to get my private environment variables. I kno...
From 2024-04-05 15:04:40
0
1
3642
Axios related errors encountered when building React applications using vite Axios works perfectly in production but when building the application I get this error. &g...
From 2024-04-05 13:20:02
0
1
326
How do I tune these cards to respond with Boostrap 4? How can I make each row display 4 cards, and of course make them stack if the screen size ...
From 2024-04-05 10:48:45
0
1
4072
CommandText property initialization problem I'm trying to materialize data into 2 (later 3) tables simultaneously using a C# console a...
From 2024-04-04 22:43:24
0
1
385
Add highest value as a column using window function I have a table like this: Query to copy data: DROPTABLEIFEXISTSunits_table;CREATETEMPTABLE...
From 2024-04-04 12:18:16
0
2
405
Related Topics
More>
Popular Recommendations
Popular Tutorials
More>
Related Tutorials
Popular Recommendations
Latest courses
Latest Downloads
More>
Web Effects
Website Source Code
Website Materials
Front End Template
About us Disclaimer Sitemap
php.cn：Public welfare online PHP training，Help PHP learners grow quickly！